Their shells protect them against predators and rough elements. Crabs have tight grips with their pincers, which allows them to grab hold of predators and fend them off. ... Their ability to condense their bodes enables crabs to take cover under rocks and other objects to hide from predators.
A hard outer shell offers protection against predators, in addition to the crab's claws, which they use to hunt prey or fight off predators.
